Process for producing high purity hydrogen from hydrocarbon gas and steam



June 8, 1965 E GORIN PRooEss Fon PRoDUcING HIGH PURITY HYDROGEN FROM HYDROCARBON GAS AND STEAM- 2 Sheets-Sheet 1 Filed April 10, 1961 w3 r E mm l 25.5 v5 mokmw @Iv 1 8.5255@ mw mzoN m23 29526.36 295:82@ r 0R52 zuwo Swzmomw 2 r3 m5 om und nho zmoowr mi www @lm 28.5 8E vm) 522mm m22 mzsom @2.2250221 mec.

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EVERETT GORIN June 8, 1965 Filed April l0. 1961 E. GORIN PROCESS FOR PRODUCING HIGH PURITY HYDROGEN FROM HYDROCARBON GAS AND STEAM 2 .Sheets-Shaw(l 2 FLUE GAS'

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Fluss uso l coNTAcTlNG' FINES HYDRoGEN EVERETT GQRIN United States Patent O l 3,183,179 PROCESS FR PRUDUClNG HIGH PURITY HY- DRGEN FRM HYDRCARBON GAS STEAM Y Everett Gorin, Pittsburgh, Pa., assigner to Consolidation Coal Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Apr. 10, 1961, Ser. No. 101,740 4 Claims. (Cl. 23-212) This invention relates to a process for the conversion of coal to hydrocarbonaceous products. More particularly, this invention relates to a process for the conversion of coal to hydrocarbonaceous liquids suitable for conversion to gasoline in a conventional gasoline refining plant.

`a result of my research I have now developed an economic process for the conversion of coal to gasoline. Via the process of my invention, gasoline may be obtained from coal at a cost of less than about 14 cents per gallon. In comparison, gasoline is produced from petroleum at a cost of about 14 to 15 cents per gallon.

Normally, a substantial amount of high purity hydrogen is required to convert coal to gasoline, consequently the cost of hydrogen frequently determines the success o r failure of a particular coal conversion process. In a copending application by VW. Retallick and myself, Serial No. 101,777, filed `of even date herewith, now US. Patent 3,108,857, issued Oct. 29, 1963, and assigned to the assignee of this invention, a novel economic process for continuously producing high purity hydrogen is described. I have found that this hydrogen production process is uniquely applicable for integration with a particular coal conversion process whereby'coal may be economically converted to hydrocarbonaceous products such as gasoline. Several byproducts produced Vin the over-all coal conversion process are employed in the hydrogen production process to produce the hydrogen needed to convert the coal. v

The primary object of this invention is to provide an economic process for the conversion of coal to'hydrocarbonaceous products, particularly hydrocarbonaceous liquid fuels such as gasoline.

Another object of this invention is to provideV arr economic process for converting coal to gasoline wherein the hydrogen utilized therein is produced from by-productsobtained from individual unit process steps in the coal conversion process.

A further object of this invention is to provide a novel process for converting coal `-to hydrocarbonaceous liquid fuels such as gasoline.

In accordance with my invention, coal is initiallyrsubjected to solventextraction to produce a mixture of Vvextract and undissolved coal (the undissolved coal is hereinafter referred to as residue). The residue is separated from the extract, for example, by ltration, and the residue is then carbonized (preferably in a uidized low temperature carbonization zone) to yield char and a distillate tar. At least a portion of the extract and the distillate tar are subsequently reacted with hydrogen in a conventional catalytic hydrocracking zone to yield offgas, i.e., non-condensable gases, and hydrocarbonaceous liquid products. The hydrocarbonaceous liquid products are suitable for final conversion to gasoline inA a conven- 3,l88,l79 Patented June 8, 1965 tional gasoline relining plant. At least a portion of the oit-gas is introduced in admixture with steam into a hydrogen production zone wherein a xed bed of steamreforming catalyst (the fixed bed having interstices between the individual catalyst particles) isrnaintained. In addition, an inventory of iiuidizable carbon dioxide acceptor particles is maintained in the hydrogen production zone in a fluidized state, at least a portion of the lluidized bed of acceptor particles being maintained within the interstices of the lixed catalyst bed. The mixture.

of off-gas and steam acts as the fluidizing medium. The off-gas reacts with steam 'in the presence of the steamreforming catalyst and the carbon dioxide acceptor particles to yield high purity hydrogen. Hydrogen is continuously recovered from the hydrogen production zone in a solids-free state, at least a portionV of which is introduced into the aforementioned catalytic hydrocracking zone. Carbon dioxide acceptor particles are separately and continuously recovered from thehydrogen production zone substantially free of steam-reforming catalyst thereby enabling the acceptor particles to be calcined and then reintroduced into the hydrogen production zone. The acceptor particles are calcined in the presence of a portion of the char recovered from the carbonization zone. The char is preferably oxidized with air to supply the heat for calcination.

For a better and more complete understanding of my invention, its objects and advantages, reference should be had to the following description and to the accompanying drawings, in which:

FIGURE 1 is 'a schematic illustration of a preferred embodiment of this invention; and

FIGURE 2 is a more detailed illustration, partly diagrammatic and partly cross-sectional, of the hydrogen production zone and the calcination zone.

Preferred embodiment The following, with reference to FIGURE l of the drawings, is a description of the preferred embodiment of this invention. Briefly, the process of this invention comprises (l) subjecting c oal to solvent extraction in a solvent extraction zone 12 to produce a mixture of extract and residue; (T2) separating the extract from the residue in a separation zone 18; (3) subjecting the residue to carbonization in a carbonization zone 24 to produce distillate tar andchar; (4) hydrocracking the distillate tar and extract in a hydrocracking zone 3.0 in the presence of hydrogen to produce olf-gas and hydrocarbonaceous liquid products (the hydrocarbonaceous liquid-products being a suitable gasoli-ne rener feedstock); (5) introducing oit-gas into a'hydrogen production zone 36 to produce the hydrogen utilized in the hydrocracking zone 39; and (6) calcining the carbon dioxide acceptor enrployed inV the hydrogen production zone in a calcination zone 46 wherein the heat for calcination is supplied `by burning a portion of the char produced in the carbonization zone 24.

traction' zone 12 wherein .the coal is reacted` with a suit' able hydrocarbonaceous solvent 14, eg., tetralin, de calin or a portion ofthe product obtained from a previous catalytic hydrocracking of extract. The coal' and the solvent react therein to yield an extract comprising -between 50 and 70 percent by weight of the MAF (moisturefree and ash-free) coal. A mixture 1 6 of extract and residue is withdrawn from the extraction zone 1 2. The operation of the solvent extraction zone 12 and the conditions maintained therein are more fully described in my copending application, Serial No. 61,518, tiled October 10,

1960, now U.S. Patent 3,018,242, issued Jan. 23, 1962,

and assigned to the assignee of this invention.

Separation zone The extract and residue mixture 16 is introduced into a conventional type separation zone 18. Preferably, the separation zone 18 is a ltration zone, however, if desired, a cyclone, centrifuge, or a conventional type settling zone may be employed in place ofthe filtration Zone. The mixture 16 is separated into residue 20 and extract 22.

Calibonization zone The residue Ztl, withdrawn from the separation zone 18, is introduced into a conventional type low temperature carbonization zone 24 maintained at a temperature in the range of about 425 to 760 C. Preferably, the carbonization zone 24 is a fluidized low temperature carbonization zone, however, if desired, other conventional devolatilization zones may be employed, for example, a rotary kiln. As a result of the reaction therein, a hydrocarbonaceous solid, that is char 26, and a distillate tar 28 are obtained.

Hydrocracking zone At least a portion of the distillate tar 28 and at least a portion of the extract 22 are introduced into a conventional type catalytic hydrocracking zone 30. The extract and tar are reacted therein with hydrogen in the presence of a hydrocracking catalyst to produce off-gas 32 and a gasoline rener feedstock 34,

The operation of the hydrocracking zone 30 and the conditions maintained therein are more fully described in my copending application, Serial No. 61,518, filed Getober 10, 17960, now U.S. Patent 3,018,242, issued Jan. 23, 1962, and assigned to the assignee of this invention.

The olf-gas 32 is obtained from the hydrocracking zone 30 as an undesirable by-product. In most coal conversion processes it is economically essential that the production of these off-gases be maintained as low as possible. Inevitably, however, a substantial amount of oit-gas is produced. The off-gas from the hydrocracking zone generally comprises in variant proportions the following materials: hydrogen, and the C1 to C.x hydrocarbons. I have found that the olf-gases obtained from the catalytic hydrocracking zone are especially suitable for use to produce hydrogen via a particular hydrogen production process (hereinafter described). Furthermore, by converting the off-gas to hydrogen in the hydrogen production zone, I am able to supply substantially all of the hydrogen required in the coal conversion process.

Hydrogen production zone and calcz'nalion zone At least a portion of the off-gas 32 is introduced into a hydrogen production zone 36 wherein the oit-gas is reacted with steam 38 in the presence of a steam-reforming catalyst and a carbon dioxide acceptor material 40. The off-gas and steam react in the presence of the steamreforming catalyst to produce hydrogen and carbon dioxide. The carbon dioxide immediately reacts with the carbon dioxide acceptor and is absorbed thereon. As a result, high purity hydrogen 4t2 is recovered from the hydrogen production zone 36, at least a portion of which is thereafter employed in the hydrocracking zone 30.

Fresh carbon dioxide acceptor must be continuously added to the hydrogen production zone 36 to absorb the carbon dioxide as it is formed therein. Correspondingly, deactivated carbon dioxide acceptor 44 is continuously withdrawn from the hydrogen production zone 36 and regenerated, that is, calcined. 'Ihe carbon dioxide acceptor 44 is regenerated in a calcination zone d6. At least a portion of the char 26 is oxidized with air d8 in the presence of the carbon dioxide acceptor 44 in the calcination zone d6 in order to desorb carbon dioxide from the acceptor particles. Regenerated acceptor 40 is withdrawn from the calcination zone 46 and reintroduced into the hydrogen production zone 36. Flue gas Si?, which comprises in large part the evolved carbon dioxide, is also withdrawn from the c'alcination zone d6.

The operation and the conditions maintained therein of both the hydrogen production zone 36 and the calcination zone 46 are more fully described in the afore-mentioned application by W. Retallick and myself, Serial No. 101,777, filed of even date herewith, now U. S. Patent 3,108,857, issued Oct. 29, 1963. However, in order to fully understand and appreciate the above coal conversion process, the following discussion, with reference to FIG- URE 2 of the drawings, is desirable. FEGURE 2 is a more detailed illustration of the hydrogen production zone 36 and the calcination zone 46. Where possible, FIGURE 2 is numbered the same as corresponding parts in FGURE 1.

Referring to FGURE 2, a substantially cylindrical reaction vessel 1110 is shown. The reaction vessel is divided by a horizontal imperforate partit-ion 112 into a hydrogen production zone 36 and a calcination zone 46. The hydrogen production zone 36 is in communication with the calcination zone t6 via a standpipe 1114. The standpipe 11d enables acceptor particles to be passed from the calcination zone 6 into the hydrogen production zone 36.

Conventional type steam-reforming catalyst in the form of a fixed bed 116 is maintained in the hydrogen production zone 36 on a grid 118. The physical arrangement of the individual catalyst particles within the fixed catalyst bed 1116 is such that interstices exist between the individual catalyst particles. For ease in understanding the operation of the hydrogen production zone 36, in the drawing the size of the interstices between the catalyst particles is exaggerated.

An inventory of carbon dioxide acceptor particles, for example, lime, is also maintained in the hydrogen production zone 36 above the grid 118. The carbon dioxide acceptor comprises particles having a size consist such that the acceptor particles may be maintained in a fluidized state within the interstices of the fixed catalyst bed 116. Normally the acceptor particles have a size consist within the range of about 8 x 200 mesh Tyler Standard screen.

A mixture 120 of olf-gas and steam is introduced into the hydrogen production zone 36. The gaseous mixture 12@ of off-gas and steam is introducedinto the yhydrogen production zone 36 such that the upward velocity of the mixture is sucient to maintain the carbon dioxide acceptor particles in the form of a fiuidized bed within the zone 36. At least a portion of the fluidized bed is maintained within the interstices of the xed bed 116 ofV steam-reforming catalyst. In addition, the uidized bed of acceptor is maintained so that acceptor particles may be continuously'and separately withdrawn from the zone 36.

The hydrogen production zone 36 is maintained under the following conditions: a temperature within the range of about 660 to 872 C.; a pressure within the range of about 73 to 295 p.s.i.; an upward gaseous velocity of steam and off-gas in the range of about 0.5 to 3.0 feet per second; and a steam to off-gas ratio in the range of about 2 to 5 mols of steamto mols of carbon contained in the off-gas. These operating conditions are favorable to both the steam-reforming reaction and the carbon dioxide acceptor reaction.

The carbon dioxide acceptor may be any of the con- Ventional type acceptors employed by those skilled in the art. Preferably, the acceptor is an alkaline earth oxide, Le.,V oxides of calcium, barium, or strontium. However, because of cheapness and abundance of supply, calcium oxide, better known as lime, is normally employed as the acceptor. l

ateatro Under the above-mentioned conditions, the steam `and the o-gas react in the presence of the reforming catalyst to form hydrogen and carbon dioxide. As previously mentioned, thev carbon dioxide immediately reacts with the carbon dioxide acceptor that is present within the interstices of the xed catalyst bed, thereby enabling high purity hydrogen to be obtained. The high purity Ahydrogen passes into a conventional type cyclone separator 122 wherein entrained solids, if any, are removed. High purity hydrogen 124 is recovered from the reaction vessel 110. Y

As the carbon dioxide acceptor particles absorb carb'on dioxide, the individual particleseventually become saturated, and thus in order to be of further use, must be regenerated, i.e., the absorbed carbon dioxide must be evolved. Carbon dioxide acceptor particles 126 are Withdrawn from the zone 36 and conveyed dispersed in a conventional carrier gas 123, for example, air, into the calcination zone 46.Y Suicient quantities of air are employed so as to maintain the acceptor particles 126 in the form of a uidized bed within the calcination zone 46 above a grid 130.

The calcination zone 46 is maintained at a temperature in the range of about 925 to 1095 C. at which temperature carbon dioxide is evolved from the acceptor particles. Preferably, the calcination is carried out at about the same pressure as within the zone 36, however, lower pressures may be employed ifdesired. 'i

In order to supplytheheat for calcination, at least a portion of the char 26 (as previously discussed with reference to FIGURE 1, the char is obtained from the carbonization zone 24) is combusted with air 12Sin the presence of theY acceptor 126 in the calcination zone 46. Fresh carbon dioxide acceptor 132 is preferably introduced with the` char in order to make up for any loss of acceptor due to attrition.

Regenerated acceptor particles are reintroduced into the hydrogen production zone 36 via the standpipe 114. Flue gas containing evolvedcarbon dioxide and any entrained acceptor nes is introduced into a conventional type cyclone separator 13 4 wherein the major portion 'of the fines is removed from thev ue gas and reintroduced into the calcination zone 46 via a conduit 136. Flue gas 13S is withdrawn from the reaction vessel 110. Preferably, the flue gas 133 is introduced into a secondary cyclone separator 140 to yield acceptor particle fines 142 and a substantially solids-free tlue glas 144.

Although the hydrogen 124 recovered from the hydrogen production zone 36 is substantially free of carbon dioxide, in some instances an even lower carbon dioxide content may be desirable.

146 to remove substantially all the carbon dioxide contained therein. Hydrogen 148 and acceptor fines 150 are recovered from the contacting zone 146. Normally, the acceptor tines 142 are slurried in water and then the slurry of water and iines is passed in countercurrent ow relationship to the hydrogen 124 in the contacting zone 146.

The contacting zone 146 also serves the purpose of cooling the hydrogen stream down close to ambient ternperature with condensation of most of the water vapor contained therein.

It is important to note that'several specific conditions must be maintained in order to ,employ the char 26 in the calcination zone 46. Charcontains a large amount of sulfur which under certain conditions Vis highly-reactive with calcium (the calcium and sulfur readily forming calcium sulfate). In order to reject the sulfur in the char as SO2 (as a part of the ue gas 138), it'is necessary to maintain a slight excess of char in the calcination zone 46 to provide a slight reducing atmosphere, i.e., a small amount of carbon monoxide is always present. is reduced and sulfur dioxide (SO2) is rejected with the Under these conditions any calcium sulfate formed illustrative of the above sulfur removal:

(Reaction I) Y CaSO4-I-4COr-CaS-l-4CO2 (Reaction II) A further detrimental feature inherent with the ,use of char is the high ash content of the char. Obviously, it is undesirable for the ash to build up in the reaction vessel 110. Thus the cyclone separator 134 is adjusted such that ash particles (which are normally much smaller than the acceptor particles) are removed from the reaction vessel 110 with the llue gas 138.

An important advantage inherent in the use of char in the calcination zone 46` is that, if necessary, it is relatively easy to increase the amount of hydrogenproduced in the hydrogen production zoneY 36 by introducing an excess of charl into the zone 46 such that a portion of the char circulates with the acceptor particles into the hydrogen production zone 36. Thus, additional hydrogen is produced via the conventional steam-carbon reaction. l It is within the scope of' this invention to employ otl'- gas produced in any one of the reaction zones of the overall coal conversion process in the hydrogen production zone4 16.V For example,` ott-gas from the solvent extraction zone 12 or the carbonization zone 24 may be introduced into the zone 36.

Example Temperature C.) 380 Solvent/coal ratio 2/1 Residence time (min.) 52

As a result of the extraction treatment, an extract yield of 59.5. percent by weight of the MAF coal is obtained.

The extract is separated from the residue in a filtration zone, and the residue is then carbonized in a fluidized low temperature carbonization zone maintained at 510 sa Y Y Thusthe acceptor Vfines 142VV are contacted with the hydrogen 124 in a contacting zone C. to'yield distillate tar and char. Portions of the tar and extract are subsequently hydrocracked in a hydrocracking zone under the following conditions:

Temperature C.) 426 Pressure (p.s.i.) 3500 Catalyst-Cobalt molybdate on an alumina base.

Hydrogen feed rate (SCF H2 per 1b. of feed) 12.8

Gasoline reliner feedstock and olf-gas are recovered from the catalytic hydrocracking zone. The off-gas, after suitable purification to recover hydrogen and to remove carbon dioxide and vhydrogen sulfide, contains the follow- The above off-gas is introduced in admixture with 3.527 mols of steam at a steam to ott-gas ratio (mol ratio) of 4.62/1 into a hydrogen production zone. Steamreforming catalyst is maintained in the' form of a tixed bed within the zone, and carbon dioxide acceptor particles l lare maintained in a fluidized bed. At least a portion of the tiuidized bed is maintained within the interstices of the fixed bed of catalyst. The zone is maintained under the following conditions:

Temperature C.) 760 Pressure (p.s.i.a.) 187 Carbon dioxide acceptor CaO Steam-reforming catalyst Nickel on tnt-alumina Space rate (vols. gas per vols. catalyst space per hour) 200 Feed rate of CaO from regeneration `(mols/mol carbon in feed gas) 1.56

As a result of the hydrogen-rich gas production and purification reactions, the following hydrogen-rich gas is obtained substantially free of any solids:

Mols/ Mol carbon Gas: in feed gas Hydrogen 3.256 CO 0.0626 CO2 0.0417 CH4 0.1106

The carbon dioxide acceptor is removed from the hydrogen production zone and is then calcined in the presence of char obtained from the carbonization zone. The char is oxidized by introducing air into the calcination zone. The conditions maintained in the calcination zone are as follows:

Temperature C.) 996 Pressure (p.s.i.a.) 162 Mols/ Mol carbon Gas: in feed gas Hydrogen 3.256 CO 0.0626

CO2 0.0200 CI-I4 0.1106

According to the provisions of the patent statutes, I have explained the principle, preferred construct-ion, and mode of operation of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

i Claim:

1. A process for producing high purity hydrogen from hydrocarbon gas and steam, which comprises (a) maintaining in a reaction zone a fixed bed of steam-reforming catalyst, said tixed catalyst bed having intersticesV between the individual catalyst particles,

(b) maintaining in said reaction zone an inventory of iiuidizable carbon dioxide acceptor particles capable .of being maintained in a fiuidized state within said fixed catalyst bed interstices,

(c) introducing a uidizing quantity of fa mixture of hydrocarbon gas and steam into said reaciton zone in contact with said fixed catalyst bed and said acceptor particles such that said acceptor particles are maintained in a uidized state within said reaction zone, at least a portion of the fluidized bed of acceptor particles being maintained within the interstices of said fixed catalyst bed,

(d) reacting said hydrocarbon gas with steam in the presence of said steam-reforming catalyst and said acceptor particles in said reaction zone to yield hydrogen from which most, but not al1, of the carbon dioxide has been removed,

(e) separately and continuously recovering acceptor particles substantially free of steam-reforming catalyst from said reaction zone,

(f) regenerating at least a portion of said recovered acceptor particles while in a tiuidized state in a calcination zone,

(g) separately recovering from said calcination zone a first and a second portion of regenerated acceptor particles, said second portion having a finer size consist than said first portion,

(h) reintroducing said first portion of the regenerated acceptor particles into said reaction zone, and

(i) contacting said -second portion of the regenerated acceptor particles with the hydrogen recovered vfrom said reaction zone under conditions to yield hydrogen substantially free of carbon dioxide.

2. The process of claim 1 wherein said carbon dioxide acceptor is an alkaline earth oxide.

3. The process of claim 1 wherein said carbon dioxide acceptor is lime.

4. The process of claim 1 where the heat required to regenerate the acceptor particles is provided by the oxidation of carbonaceous solid-s in admixture with -said acceptor particles in said calcination zone.

References Cited by the Examiner UNITED STATES PATENTS MAURICE A. BRINDISI, Primary Examiner.

'ALPHONSO D. SULLIVAN, Examiner. 

1. A PROCESS FOR PRODUCING HIGH PURITY HYDROGEN FROM HYDROCARBON GAS AND STEAM, WHICH COMPRISES (A) MAINTAINING IN A REACTION ZONE A FIXED BED OF STEAM-REFORMING CATALYST, SAID FIXED CATALYST BED HAVING INTERSTICES BETWEEN THE INDICDUAL CATALYST PARTICLES. (B) MAINTAINING IN SAID REACTION ZONE AN INVENTORY OF FLUIDIZABLE CARBON DIOXIDE ACEPTOR PARTICLES CAPABLE OF BEING MAINTAINED IN A FLUIDIZED STATE WITHIN SAID FIXED CATALYST BED INTERSTICES, (C) INTRODUCING A FLUIDIZING QUANTITY OF A MIXTURE OF HYDROCARBON GAS AND STEAM INTO SAID REACTION ZONE IN CONTACT WITH SAID FIXED CATALYST BED AND SAID ACEPTOR PARTICLES SUCH THAT SAID ACCEPTOR PARTILES ARE MAINTAINED IN FLUIDIZED STATE WITHIN SAIDREACTION ZONE, AT LEAST A PORTION OF THE FLUIDIZED BED OF ACCEPTOR PARTICLES BEING MAINTAINED WITHIN THE INTERSTICES OF SAID FIXED CATALYST BED, (D) REACTING SAID HYDROCARBON GAS WITH STEAM IN THE PRESENCE OF SAID STEAM-REFORMING CATALYST AND SAID ACCEPTOR PARTICLES IN SAID REACTION ZONE TO YIELD HYDROGEN FROM WHICH MOST, BUT NOT ALL, OF THE CARBON DIOXIDE HAS BEEN REMOVED, (E) SEPARATELY AND CONTINUOUSLY REVOVERING ACCEPTOR PARTICLES SUBSTANTIALLY FREE OF STEAM-REFORMING CATALYST FROM SAID REACTION ZONE, (F) REGENERATING AT LEAST A PORTION OF SAID RECOVERED ACCEPTOR PARTICLES WHICLE IN A FLUDIZED STATE IN A CALCINATION ZONE, (G) SEPARATELY RECOVERING FROM SAID CALCINATION ZONE A FIRST AND A SECOND PORTION OF REGENERATED ACCEPTOR PARTICLES, SAID SECOND PORTION HAVING A FINER SIZE CONSIST THAN SAID FIRST PORTION, (H) REINTRODUCING SAID FIRST PORTION OF THE REGENERATED ACCEPTOR PARTICLES INTO SAID REACTION ZONE, AND (I) CONTACTING SAID SECOND PORTION OF THE REGENERATED ACCEPTOR PARTILES WITH THE HYDROGEN RECOVERED FROM SAID REACTION ZONE UNDER CONDITIONS TO YIELD HYDROGEN SUBSTANTIALLY FREE OF CARBON DIOXIDE. 